The Bristol Type 450

The “Filton Flyers”


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The Company Team Racing cars were fabricated for the seasons of 1953 to 1955 inclusive, and contested top ranking endurance events in the 2 litre class – at the Le Mans (24 hours) race and at the Rheims (12 hours) race, often achieving wins in their Class and also winning Team prizes.

1953-style 450 'camel' body Nearside view: click for 54K image
The 450 coupés in 1953

1953

In 1953 the first series was introduced – a rather ungainly twin-finned fixed head coupé style, with lights attached almost as an afterthought to the surface of the body.

405 wheel: click for 74Kb image
450 road wheel

The starting-point was the ERA G-type, which by 1952 was fitted with Bristol engines, and driven by the young Stirling Moss, who was not very impressed with it. Bristol took on the interesting wheel design (see left): the wheel was essentially just a rim with five small lugs for attachment to “spiders”. They were much lighter than ordinary road wheels, and the rear hubs were made so that the outer flexible joint of each half-shaft protruded, thus enabling a damaged half-shaft to be replaced without disturbing the road wheel and brake assemblies. Speedy wheel rim and tyre switches were made possible at the pits using a multi-barrelled powered spanner designed by Vivian Selby at the Bristol engineering workshops. The spanner removed all of the wheel nuts at once, retained them whilst the rims plus tyres were switched, then ran up all of the nuts on to their threads simultaneously, applying the correct amount of torque. The spanner was reported to be a bit heavy to handle, but ran like a Swiss watch. This was one of several time-saving contrivances, such as magnetic fuel and oil filler cap closures, that enabled one 450 to spend just 15 minutes in the pits during an entire 24-hour race.

The new Bristol construction, designed by the Aircraft Division, was wind tunnel tested and built in the time-honoured way using wooden “bucks” to shape the frame, to which shaped alloy panels were then attached. Though slow and labour-intensive, this method gave a light and very strong build. Whereas the G-type had used 6" magnesium zirconium for the frame, Bristol used 4½" thin-wall steel tubing, with no important weight penalty. There were outboard disc brakes at the front, with inboard rear disc brakes and gearbox at the rear.

Meanwhile, the Bristol BS racing engine was undergoing intensive development by Percy Kemish — mainly to get more power at first. After 200 hours at the dynamometer, he was able to demonstrate a reliable 140BHP, enough to propel the car at 143 mph on the Brabazon straight at Filton. His racing engine was designated the BSX.

At the 1953 Le Mans 24-hour race, the car driven by Lance Macklin and Graham Whitehead completed only 29 laps before the crankshaft balance weights decided to go exploring on their own; the other, driven by Tommy Wisdom and Jack Fairman, went on for a few more hours before a similar fate befell them; and so neither car was to finish that year. Many engineering and aerodynamic lessons were learned. Kemish's team immediately rebuilt the engines — without balance weights from now on.

At the subsequent 12-hour Reims event, the Fairman/Wilson car won the 2-litre class at 92.65 mph. Later in the year, a new nose section was designed, with the lamps now faired in, the main intake streamlined, and in place of the “power bulge” on the bonnet, a new separate intake ducting air to the Solex carburettors.

later 450 coupé

Late in the year, one of the cars was taken to Montlhéry and established the following 2-litre Class E records: 200 miles @ 125.87mph; 500km @ 116.10mph; 1000km @ 115.49mph; 3 hrs @ 116.42mph; 6 hrs @ 115.43mph; and 500 miles @ 115.74mph. Once these had been secured, the car was sent out for a final lap, to see what it could really do, and an average lap speed of 126mph was achieved.

Following Rheims, the side panels, just behind the front wheels, were depressed to facilitate the flow of hot air from around the brake drums. Later, the rear was restyled to give a 14% reduction in drag by reducing the rear fins. The fins were retained, however, as they greatly enhanced the stability of the car, particularly when cornering.

1954

BSX engine with Kemish 'straighteners'

During the winter, Kemish worked on the air intake, mainly to improve carburation and exhaust efficiency. He experimented with large trumpets, not wishing to increase the overall height. To increase the air speed, and collect any petrol spray, he fitted inverted internal cones which became known as Kemish Straighteners. This modification was so successful that it was fitted to all the team cars.

A new cylinder head was developed. Often called “the six port head”, it was really a twelve port head. It enabled special Solex carburettors of the twin-choke type to be used, with each of the six hemispherical combustion chambers having its own individual choke. Only 12 of these special heads were ever made. There was a new exhaust system too: individual pipes were taken from the single exhaust manifold and then paired 1-6, 2-5, 3-4. The triple pipes emerged just in front of the nearside rear wheel. These modifications increased the power to 155bhp at 6000 rpm.

For the 1954 season, it was decided to field three cars in a new livery — “apple green” instead of the dark British Racing Green of 1953. The third car was now crewed by Mike Keen and Trevor Line, and the first by Peter Wilson and Jim Mayers, whilst the second remained with Wisdom and Fairman. A then unknown and taciturn reserve, who never actually drove for Bristol, was Jack Brabham.

At Le Mans, things went well. By breakfast time on Sunday 13 June 1954, all real opposition in the 2-litre class had vanished, with Bristol the only team intact. Results were: Wilson/Mayers 1st in class, 7th overall, having covered 3503 km (2178 miles) at 90.76 mph; Wisdom/Fairman 2nd in class, 8th overall, 3463.13 km; Keen/Line 3rd in class, 9th overall, 3437.16 km. They won the team prize — only the third time the prize had been awarded in the history of Le Mans. The weather had been terrible: out of 57 who started, only 18 cars finished.

1955

Click for 82Kb image of 450s at Le Mans
450s at Le Mans 1955

Perhaps because of misting-up in the atrocious 1954 weather, for 1955 the cars were fitted out with open 2-seater bodies of an entirely new design, not unlike the Jaguar D-type. Their shape was “determined by eye”. The most notable feature was the substantial single asymmetric fin just behind the driver's head.

More engine tuning led to a new exhaust system, which further developed the 1954 6-into-3 by collecting the 3 into a final pipe of larger bore. David Summers made a modification, “part Watts, part Summers” to the rear suspension to ensure no deviation fore nor aft. Kemish, the engine expert, later recalled being driven at 152 mph (245 kph) down the straight by Lance Macklin.

Click for 185Kb image of 450 at 1955 Le Mans
Only known image of 450 at Le Mans 1955

At the 24-hour race, held on the weekend 11-12 June, the leading Bristol averaged 100 mph for the first 12 hours, running 5th overall. Hopeful of winning the team prize again, Selby slowed Wilson and Mayers down, and they finished first in the 2-litre class, 7th overall, having covered 2270 miles at 94.6 mph. Keen and Line were second in class and the Wisdom/Fairman car third, 9th overall. Observers were impressed that using the low-octane French petrol, the cars averaged 15 mpg during the race.

Sadly, however, the 1955 Le Mans was to be most remembered for the horrendous Levegh disaster. Briefly, Pierre Levegh was approaching the pit area at speed in his works Mercedes-Benz just as another car was dodging Mike Hawthorn's Jaguar, which was pulling in for a pit stop. Levegh struck the avoiding car and was deflected across the track into a safety barrier. Levegh was killed instantly, but the wreckage of his car was hurled over the barriers and into the crowd. To this day it is unknown whether the resulting carnage took 93 or 94 lives. The organizers took the view that if they stopped the race, the exit of 200,000 spectators would impede the rescue efforts. Thus it was that the other cars continued, unaware of the extent of the tragedy that had taken place early on.

Aftermath

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Front view of the 450 Le Mans Team Road Race car

As the results became known, the world resiled from motor racing. The 12-hour Rheims event was cancelled. Switzerland, among others, banned the sport outright. The Bristol Aeroplane Company donated its prize money to the disaster fund. Perhaps this was not the right image to be associated with Bristol cars.

Another disaster had recently affected the British aviation industry: the failure of a number of de Havilland Comet jet airliners. An inquiry revealed in February 1955 that the cause was metal fatigue. Suddenly, the UK government was demanding far more exhaustive testing of the new Bristol Britannia aircraft, and this was proving punitively expensive. There was simply no more money for motor racing at Bristol.

And if that wasn't enough, later that year, Mike Keen and Jim Mayers, both regular team drivers, were killed at separate events. Soon afterwards, the Racing Department was disbanded.

There had been plans to create a road version of the 450. To reduce the vehicle's height, it was intended to mount the engine at 45° in a space frame chassis. A de-tuned engine was tested, producing 170 bhp at 6000 rpm, and could be revved up to 7000 in safety. But it was realised that such a car would appeal to only a very few wealthy enthusiasts; so this project was abandoned also.

With the disappearance of Bristol from motor racing, questions soon began to be asked as to the fate of the three team cars. Before long, a rumour had arisen that they had all been broken up, to prevent their “getting into the wrong hands”. More fanciful tales involved one single car being preserved for a wealthy American enthusiast, who would fly to Britain once a year, retrieve it from its secret garage and take it for a surreptitious drive at dead of night.

That such rumours should have arisen is understandable, given that no 450 was to be seen again for over 35 years. Only lately has the truth emerged.

The Survivor

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Rear detail of 450 Le Mans Team car

It seems that after the racing project was killed, the senior apprentices at the factory were indeed set to dismantle the three team cars. However, that was not the end: the best of the parts were then selected and reassembled into a single exemplar, built to a standard that would be worthy of the memory of Bristol's brief but glorious racing history.

It does not have a BSX engine, and it is thought that none survives today. However, the present engine (a 100B2) was specially rebuilt to equivalent standard and is equipped with one of the original 12-port heads that were fitted to the 1955 Le Mans cars.

Click for 133Kb image
Cockpit of the last 450

This sole survivor was kept for many years by the Owner (and Managing Director) of Bristol Cars Ltd, that well known and acclaimed post WW2 racing driver Anthony Crook. In the early 1990s, this unique piece of British motor racing heritage passed into the hands of a long time Bristol enthusiast, competitor and collector. It is kept well maintained, in good order, and is still occasionally displayed in road and selected track events. Naturally its very high gearing does not lend itself to effective use in competition in today's short track Historic Racing events.

This page, generated 2018/12/12 12:35:14, was last modified 2017/05/24 12:09:58